/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.catalina.tribes.transport;

import org.apache.catalina.tribes.Member;
import org.apache.catalina.tribes.util.StringManager;
import org.apache.juli.logging.Log;
import org.apache.juli.logging.LogFactory;

import java.io.IOException;
import java.util.List;

/**
 * <p>Title: </p>
 * <p>
 * <p>Description: </p>
 * <p>
 * <p>Company: </p>
 *
 * @author not attributable
 * @version 1.0
 */
public abstract class PooledSender extends AbstractSender implements MultiPointSender {

	protected static final StringManager sm =
			StringManager.getManager(Constants.Package);
	private static final Log log = LogFactory.getLog(PooledSender.class);
	private SenderQueue queue = null;
	private int poolSize = 25;
	private long maxWait = 3000;

	public PooledSender() {
		queue = new SenderQueue(this, poolSize);
	}

	public abstract DataSender getNewDataSender();

	public DataSender getSender() {
		return queue.getSender(getMaxWait());
	}

	public void returnSender(DataSender sender) {
		sender.keepalive();
		queue.returnSender(sender);
	}

	@Override
	public synchronized void connect() throws IOException {
		//do nothing, happens in the socket sender itself
		queue.open();
		setConnected(true);
	}

	@Override
	public synchronized void disconnect() {
		queue.close();
		setConnected(false);
	}

	public int getInPoolSize() {
		return queue.getInPoolSize();
	}

	public int getInUsePoolSize() {
		return queue.getInUsePoolSize();
	}

	public int getPoolSize() {
		return poolSize;
	}

	public void setPoolSize(int poolSize) {
		this.poolSize = poolSize;
		queue.setLimit(poolSize);
	}

	public long getMaxWait() {
		return maxWait;
	}

	public void setMaxWait(long maxWait) {
		this.maxWait = maxWait;
	}

	@Override
	public boolean keepalive() {
		//do nothing, the pool checks on every return
		return (queue == null) ? false : queue.checkIdleKeepAlive();
	}

	@Override
	public void add(Member member) {
		// no op, senders created upon demands
	}

	@Override
	public void remove(Member member) {
		//no op for now, should not cancel out any keys
		//can create serious sync issues
		//all TCP connections are cleared out through keepalive
		//and if remote node disappears
	}
	//  ----------------------------------------------------- Inner Class

	private static class SenderQueue {
		PooledSender parent = null;
		private int limit = 25;
		private List<DataSender> notinuse = null;

		private List<DataSender> inuse = null;

		private boolean isOpen = true;

		public SenderQueue(PooledSender parent, int limit) {
			this.limit = limit;
			this.parent = parent;
			notinuse = new java.util.LinkedList<DataSender>();
			inuse = new java.util.LinkedList<DataSender>();
		}

		/**
		 * @return Returns the limit.
		 */
		public int getLimit() {
			return limit;
		}

		/**
		 * @param limit The limit to set.
		 */
		public void setLimit(int limit) {
			this.limit = limit;
		}

		public int getInUsePoolSize() {
			return inuse.size();
		}

		public int getInPoolSize() {
			return notinuse.size();
		}

		public synchronized boolean checkIdleKeepAlive() {
			DataSender[] list = new DataSender[notinuse.size()];
			notinuse.toArray(list);
			boolean result = false;
			for (int i = 0; i < list.length; i++) {
				result = result | list[i].keepalive();
			}
			return result;
		}

		public synchronized DataSender getSender(long timeout) {
			long start = System.currentTimeMillis();
			while (true) {
				if (!isOpen) throw new IllegalStateException("Queue is closed");
				DataSender sender = null;
				if (notinuse.size() == 0 && inuse.size() < limit) {
					sender = parent.getNewDataSender();
				} else if (notinuse.size() > 0) {
					sender = notinuse.remove(0);
				}
				if (sender != null) {
					inuse.add(sender);
					return sender;
				}//end if
				long delta = System.currentTimeMillis() - start;
				if (delta > timeout && timeout > 0) return null;
				else {
					try {
						wait(Math.max(timeout - delta, 1));
					} catch (InterruptedException x) {
					}
				}//end if
			}
		}

		public synchronized void returnSender(DataSender sender) {
			if (!isOpen) {
				sender.disconnect();
				return;
			}
			//to do
			inuse.remove(sender);
			//just in case the limit has changed
			if (notinuse.size() < this.getLimit()) notinuse.add(sender);
			else
				try {
					sender.disconnect();
				} catch (Exception e) {
					if (log.isDebugEnabled()) {
						log.debug(sm.getString(
								"PooledSender.senderDisconnectFail"), e);
					}
				}
			notify();
		}

		public synchronized void close() {
			isOpen = false;
			Object[] unused = notinuse.toArray();
			Object[] used = inuse.toArray();
			for (int i = 0; i < unused.length; i++) {
				DataSender sender = (DataSender) unused[i];
				sender.disconnect();
			}//for
			for (int i = 0; i < used.length; i++) {
				DataSender sender = (DataSender) used[i];
				sender.disconnect();
			}//for
			notinuse.clear();
			inuse.clear();
			notify();


		}

		public synchronized void open() {
			isOpen = true;
			notify();
		}
	}
}